Macedonian police fired tear gas and stun guns Monday as several hundred Iraqi and Syrian refugees, frustrated at days of delays in crossing the Greek-Macedonian border, broke down a gate on a nearby rail crossing.

Thousands of people have been stuck for days at Greece's northern border, overflowing from a packed refugee camp at Idomeni into the surrounding fields as they waited for Macedonian authorities to let them continue their trek through the Balkans. Only a tiny trickle of people from specific countries...